Environmental Durability Testing of Structural Adhesives. Part III. Reliabond 500/Reliabond 398

摘要

A program has been conducted to investigate the durability of a 350 F (121 C) curing modified epoxy structural adhesive in an elevated temperature, high humidity environment while under stress. Durability was assessed with three different types of environmental exposure. Unstressed lap shear specimens were exposed to both a 140 F (60 C)/95-100% R.H. environment and a 140 F (60 C) water soak and residual strength tests were conducted after various aging intervals. Stressed lap shear specimens were exposed to a 140 F (60 C)/95-100% R.H. environment and time-to-failure recorded. The unstressed agings produced a progressive loss of residual strength and a progressive increase in the amount of adhesive (interfacial) failure with increased aging time. The stressed agings produced times-to-failure at least as long as those previously obtained (AFML-TR-78-35, Part I) for the PL-729-3/PL-728 and AF-143-2/EC-3917 adhesive/primer systems on the same substrates and surface preparations. Had exposure times been extended beyond 2400 hours, the R398/R500 system may have proven more durable than the two previously tested systems. (Author)